1. Field of the Invention
The invention relates to a high voltage operational amplifier and has particular utility in high voltage feedback of electrostatic voltmeters.
2. Description of the Prior Art
The prior art discloses the use of a high voltage operational amplifier having high frequency synchronized inverters in combination with a demodulator, which has excellent transient response but involves operating voltages exceeding twice the maximum output voltage. Note for example applicant's U.S. Pat. No. 3,887,877 for "Feedback Electrostatic Voltmeter." An operational amplifier having light sources optically coupled to photoconductor elements in the output circuit thereof is also disclosed in the art, as, for example, in applicant's U.S. Pat. No. 3,590,251. While the operational amplifier disclosed in this latter patent provides an efficient amplification technique whose output voltage capability can approach the supply voltage utilized, its speed-of-response is limited by the relatively slow speed-of-response of the available photoconductors.